1. Field of the Invention
The invention relates to lithium-containing assistants and to their use for textile dyeing and printing.
When, in textile dyeing, sulpho-containing reactive or direct dyes are used for native and regenerated cotton, anionic textile auxiliaries are used for improving the passage of the cloth and for levelling the fabric appearance.
A large number of dyes have only limited solubility and can precipitate unevenly on cotton, causing unlevel dyeings. The use of conventional dyeing assistants does not allow a satisfactory improvement to be achieved in all cases.
Moreover, wetting agents are used for improving the wettability and liquor penetration of the material to be dyed. These anionic surfactants were hitherto added to the dyebath in the form of their sodium or potassium salts, for example dialkyl phosphates or diaryl phosphates, fatty alcohol sulphonates or fatty alcohol sulphates, and anionic dispersants, in particular the sodium or potassium salts of sulphonated, aromatic condensation products, for example of naphthalene, formaldehyde and sulphuric acid.
When fibre mixtures, for example fibre mixtures composed of cotton and polyester or cotton and polyamide, are dyed, it is customary to add non-ionic surfactants to the dyebath, for example alkoxylated fatty alcohols, alkoxylated alkylphenols and alkoxylated synthetic hydrophobic parent structures.
To increase the solubility of the dye in water, it is customary to add assistants to the dyebath or to the padding dyestuff liquor, for example .epsilon.-caprolactam, polyvinylpyrrolidones and alkylamidedicarboxylic acids.
The disadvantage here is, inter alia, that the dyeing is still unlevel due to the fact that the dye is not distributed uniformly on the fibre.
2. Description of the Related Art
It has also been disclosed to carry out dyeings in the presence of Li.sup.+. EP-A-511,571 describes the addition of water-soluble Li compounds, in particular LiHCO.sub.3 to the aqueous preparation of the dye. JP-A-72.43155 describes the dyeing of fibres and plastics using cationic dyes in the presence of surface-active compounds, which can be Li salts.